Mitochondrial DNA is different from nuclear DNA because
A.
it is inherited only from the mother
B.
it is inherited only from the father
C.
it is double helix in shape
D.
it is not useful in forensic science
A. it is inherited only from the mother
The correct answer is:
A. it is inherited only from the mother
Mitochondrial DNA (mtDNA) is different from nuclear DNA because it is solely inherited from the mother. This is because, during sexual reproduction, the mitochondria from the father's sperm do not generally make it into the fertilized egg. Instead, the mitochondria that provide the mtDNA are passed down exclusively from the mother's egg.
The correct answer is A. Mitochondrial DNA is different from nuclear DNA because it is inherited only from the mother.
To understand why mitochondrial DNA is inherited only from the mother, we need to first understand some basics of genetics. Humans have two types of DNA: nuclear DNA and mitochondrial DNA. Nuclear DNA is located in the nucleus of our cells and is inherited from both parents. It carries the majority of our genetic information and determines traits such as physical appearance and susceptibility to certain diseases.
On the other hand, mitochondrial DNA is located in the mitochondria, which are small membrane-bound structures found in our cells. Mitochondria are often referred to as the "powerhouses" of the cell because they produce energy needed for various cellular processes.
Mitochondrial DNA is unique because it is only passed down from the mother to her offspring. This is because during fertilization, the father's sperm contributes only its nuclear DNA to the developing embryo, while the mother's egg provides both nuclear DNA and mitochondrial DNA. Therefore, all of an individual's mitochondria, and hence their mitochondrial DNA, are derived from their mother.
This pattern of inheritance makes mitochondrial DNA useful for studying evolutionary relationships and tracing maternal lineages within a population. Since it is passed down from generation to generation without recombination (a process where DNA from both parents is reshuffled), mitochondrial DNA accumulates mutations at a relatively steady rate. These mutations serve as genetic markers that can be used to track and compare maternal lineages.
In contrast, nuclear DNA, which is inherited from both parents, undergoes recombination during the formation of sperm and eggs. This shuffling of genetic material makes nuclear DNA a better tool for determining overall genetic relatedness, identification, and forensic science applications.
Therefore, option A is the correct answer as it accurately describes one of the key differences between mitochondrial DNA and nuclear DNA.